水氮处理对谷子内源激素脱落酸和光合作用特性的影响

Effects of water and nitrogen treatment on endogenous hormone abscisic acid and photosynthetic characteristics of foxtail millet

为探究氮肥与干旱处理对谷子生理特性的影响,以济谷22为材料,采用盆栽法研究不同水、氮处理对谷子内源激素脱落酸(ABA)、叶绿素含量、光合作用特性及水、氮利用效率的影响。设置3种水分处理:正常水分(CK,田间持水量的60%~70%)、苗期干旱(W_(1),田间持水量的30%~40%)、孕穗期干旱(W_(2),田间持水量的30%~40%)及2种施氮量处理:施氮(N_(150),N 150 kg/hm^(2))、不施氮(N_(0)),生长期间旱棚防雨。结果表明:受到水分胁迫时,叶片中的ABA含量升高,施氮水平下升高幅度较大;根中ABA含量也会升高,但其在不施氮水平下升高幅度较大。开花期不同处理光-光合响应曲线有显著差异,苗期干旱施氮处理优势明显。开花期叶片荧光性能存在较大差异,受到水、氮胁迫时,光系统Ⅱ潜在的最大光化学效率、反应中心所吸收的光子中用于电子传递的量子产额值降低,反应中心所吸收光子中用于热耗散的量子比率上升,以吸收光能为基础的性能指数急剧下降,孕穗期干旱施氮处理的j点的相对可变荧光强度显著高于对照,孕穗期干旱且不施氮的以吸收光能为基础的性能指数最低,反映单位反应中心捕获的用于电子传递的能量值最高。不同水、氮处理的谷子抽穗后,随着时间的推移,SPAD值逐渐降低,施氮处理明显提高了叶片的SPAD值。不同处理间比较以施氮处理下苗期干旱水分利用效率最高,不施氮处理的氮素利用效率明显高于其他处理。同一水分处理下,施氮处理的水分利用效率显著高于不施氮处理,氮素利用效率表现为相反趋势。苗期干旱施氮处理通过提高叶片SPAD值、花期净光合速率,显著提升了光合作用,水分和氮肥利用率显著提高,保证谷子达到相对稳定的产量。

In order to explore the effects of nitrogen fertilizer and drought treatment on the physiological characteristics of foxtail millet,the effects of different water and nitrogen treatments on endogenous hormone abscisic acid(ABA),chlorophyll content,photosynthetic characteristics and water and nitrogen use efficiency of foxtail millet were studied by pot culture with“Jigu 22”as material.Three water treatments were set up:normal water(CK,60%-70%of field water capacity),drought at seedling stage(W_1,30%-40%of field water capacity),drought at booting stage(W_2,30%-40%of field water capacity)and two nitrogen treatments were conducted:N 150 kg/hm^(2)(N_(150))and no nitrogen(N_0).A rainproof shelter was used to protect the pots against rain during growth.The results showed that ABA content in leaves was increased under water stress,and increased greatly under nitrogen application.ABA content in roots was also increased,but the increase was more without nitrogen application.The photosynthetic response curves of different treatments at flowering stage were significantly different,and the treatment of drought at seedling stage and nitrogen application had obvious advantages.There were great differences in the fluorescence properties of leaves in flowering stage.Under water and nitrogen stress,the potential maximum photochemical efficiency of photosystem II,the quantum yield of photons absorbed by the reaction center for electron transfer decreased,the quantum ratio of photons absorbed by the reaction center for heat dissipation increased,and the performance index based on light energy absorption decreased sharply.The relative variable fluorescence intensity content of j point in the dry nitrogen treatment at booting stage was significantly higher than that in the control.The performance index based on light energy absorption was the lowest in the dry nitrogen treatment at booting stage,and the energy captured by unit reaction center for electron transport was the highest.After heading of foxtail millet with different water and nitrogen treatments,the SPAD value was decreased with time,and the nitrogen application treatment significantly increased the SPAD value of leaves.The water use efficiency of drought at seedling stage and nitrogen application treatment was the highest,and the nitrogen use efficiency of no nitrogen application treatment was significantly higher than that of other treatments.Under the same water treatment,the water use efficiency of nitrogen application treatment was significantly higher than that of no nitrogen application treatment,while the nitrogen use efficiency showed the opposite trend.Drought treatment at seedling stage with nitrogen application significantly improved photosynthesis by increasing SPAD value of leaves and net photosynthetic rate at flowering stage,and significantly increased water and nitrogen utilization rate,so as to ensure relatively stable yield of foxtail millet.